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r_towle |
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#1
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Custom Member ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() Group: Members Posts: 24,705 Joined: 9-January 03 From: Taxachusetts Member No.: 124 Region Association: North East States ![]() ![]() |
Hi, I searched (Phrase rod and ratio) and got over 1000 hits...
I think search just does not work right...I cant figure it out... Anyways... What is the optimum rod ratio for a type 4. I would like to hear lots of opinions on this one. Rich |
smontanaro |
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#2
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Senior Member ![]() ![]() ![]() Group: Members Posts: 1,190 Joined: 3-June 05 From: Evanston, IL Member No.: 4,197 Region Association: Upper MidWest ![]() |
Try
+rod +ratio Skip |
jd74914 |
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#3
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Its alive ![]() ![]() ![]() ![]() Group: Members Posts: 4,841 Joined: 16-February 04 From: CT Member No.: 1,659 Region Association: North East States ![]() |
According to BrettW in this thread the optimal type IV ratio is 1.70 to 1.80.
http://www.914world.com/bbs2/index.php?sho...c=4964&st=0 |
jd74914 |
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#4
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Its alive ![]() ![]() ![]() ![]() Group: Members Posts: 4,841 Joined: 16-February 04 From: CT Member No.: 1,659 Region Association: North East States ![]() |
Hmm . . . this graph migh interest you, as well as the article I bookmarked it in a while ago. (IMG:style_emoticons/default/smile.gif)
http://www.e30m3performance.com/tech_artic...ratio/index.htm (IMG:http://www.e30m3performance.com/tech_articles/engine-tech/rod-ratio/accel-1.gif) |
Twystd1 |
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#5
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You don't want to know... really..... ![]() ![]() ![]() ![]() Group: Members Posts: 2,515 Joined: 12-September 04 From: Newport Beach, California Member No.: 2,743 ![]() |
What are you looking for as far as HP / TQ..????
And at what RPM will this engine be living in most of the time? Clayton |
Jake Raby |
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#6
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Engine Surgeon ![]() ![]() ![]() ![]() ![]() Group: Members Posts: 9,398 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States ![]() |
Optimum rod ratio is dictated by the RPM range goal for the engine as well as the cam and head work as well as the longevity goal...
For engines I design I shoot for 1.75:1 for street engines, but I have some powerful combos that run as little as 1.55:1. Our race engines that sustain RPM use 2:1 or more There is no perfect rod ratio for the engine. "Its all in the combo". as always. |
Borderline |
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#7
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Senior Member ![]() ![]() ![]() Group: Members Posts: 720 Joined: 8-February 05 From: San Juan Bautista, CA Member No.: 3,577 Region Association: Northern California ![]() |
Dema Elgin (local SF Bay area cam grinder) has an interesting article on engine design including rod ratios. lElgin Cams
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